The electro-spinning method is to prepare a fiber using electrostatic force. The method has not been focused for a long time but has been actively researched from recent decade in industrial separator material, tissue engineering and biological fields such as biomaterial scaffold, drug carrier or biosensor [Polymer Int'l, 2008, 57, 385-389; Biomaterials, 2008, 29, 1989-2006; Polymer, 2008, 49, 2387-2425; Polymer, 1999, 40, 4585-4592].
The electro-spinning method is to prepare a fiber using the interaction between surface tension and an electrostatic repulsion of electrical charge which is driven in a liquid, when a sufficiently high voltage is applied to a liquid droplet. Compared with convention dry melt spinning and wet spinning, it has simple mechanism and using method relatively, and has advantage of production for a fiber with various diameter such as several nm to tens nm.
Generally, the electrospun fiber has large surface area per unit volume due to relatively small diameter and good mechanical properties, the surface of fiber can be modified with specific functional group, and the fiber can be used for easily preparing non-woven fabric with two or three dimensional structure of minute pores having a diameter of several micrometer or less [Composites Science and Technology, 2003, 63, 2223-2253; J. Biomater. Sci. Polym. Edu. 2006, 17, 1039-1056; 2010, 13(1), 32-50].
Because of such advantages, the electrospun fiber is expected to be used for new materials for next-generation in various technical fields, for examples, a biomaterial scaffold required for cell generation of blood vessel, bone, ligament and the like [Int'l J. Biolog. Macromol., 2009, 45, 504-510], a drug carrier [Acta Biomaterialia, 2010, 6, 102-109; Annu. Rev. Mater. Res., 2006, 36, 333-368; Current Pharmaceutical Design, 2006, 12, 4751-4770; PCT WO 2009/078924], highly-efficient filter material such as HEPA filter (high efficiency particulate air filter) or ULPA filter (ultra low penetration air filter) [Journal of Industrial Textiles, 2007, 37, 151; Current Applied Physics, 2006, 6, 1030-1035].
However, the kinds of fiber which can be prepared by the electro-spinning method are very limited. Furthermore, the various field where the electrospun fiber is expected to be applied requires a porous material, but the development of materials capable of be applied for the field is still insignificant until now.